SECR N1 Class

The SECR N1 class was a type of 3-cylinder 2-6-0 ('mogul') steam locomotive designed by Richard Maunsell for mixed traffic duties, initially on the South Eastern and Chatham Railway (SECR), and later operated for the Southern Railway (SR). The N1 was a development of the basic principles established by the Great Western Railway's (GWR) Chief Mechanical Engineer (CME) George Jackson Churchward and by Maunsell's previous N class design.

The N1 prototype was the result of modifications made to N class No. 822 during construction in 1922. The locomotive became operational in 1923 and used parts interchangeable with other Maunsell locomotive classes. The prototype N1 was the only member of the class constructed before the SECR became part of the Southern Railway at the Grouping in 1923, and featured a variant of the Gresley conjugated valve gear designed by Harold Holcroft. The class set the precedent for the Southern Railway's subsequent 3-cylinder designs.

The N1s compared favourably with the N class, although the type showed little improvement in performance. More of the class were built when it became clear that the type's smaller cylinders provided greater route availability. A total of six engines were built. The N1 class was primarily used on the Eastern section of the Southern Railway network, and used by the Southern Region of British Railways (BR) from 1948. The N1s gave valuable service until they were withdrawn in 1962. None were preserved.